GMC Cadillac CTS 2004 Owner's Manual page 152

These sensors monitor the solar radiation and the air
inside your vehicle, then use the information to maintain
the selected temperature by initiating needed
adjustments to the temperature, the fan speed and the
air delivery system. The system may also supply
cooler air to the side of the vehicle facing the sun. The
recirculation mode will also be activated, as necessary.
Do not cover the sensors or the automatic climate
control system will not work properly.
3-32
There is also an interior
temperature sensor
located to the right of the
steering wheel on the
instrument panel.
Defogging and Defrosting
Fog on the inside of windows is a result of high humidity
(moisture) condensing on the cool window glass. This
can be minimized if the climate control system is
used properly. There are two modes to clear fog from
your windshield. Use the defog mode to clear the
windows of fog or moisture and warm the passengers.
Use the defrost mode to remove fog or frost from
the windshield more quickly.
yN z
(Mode): Press this button until defog appears
on the display.
-
(Defog): This mode directs the air between the
windshield, floor outlets and side windows. When you
select this mode, the system turns off recirculation
and runs the air-conditioning compressor unless
the outside temperature is at or below freezing.
The recirculation mode is cancelled when you enter
defog mode. If you select recirculation while in defog
mode, it will be cancelled after 10 minutes.